Many prior art data acquisition devices, such as digital storage oscilloscopes, require that their acquisition parameters be adjusted. Their acquisition parameters, including trigger level, voltage range, number of points (record length), sampling rate, and the pre-trigger amount, have optimal values for the equipment being used and the waveform or input signal being acquired. For example, the voltage range used to acquire an input signal should be greater than the magnitude range which the input signal spans to acquire the entire signal without clipping of the maximum and/or minimum data points. However, increasing the voltage range decreases the resolution in most systems. Therefore, the optimal voltage range is the smallest range that does not clip the input signal.
Optimal values for other parameters must be determined together. For example, the sampling rate and record length should be selected together such that the sampling rate is as fast as necessary to prevent aliasing, but slow enough to record the entire waveform for the selected record length.
Many prior art data acquisition systems require that the acquisition parameters be manually adjusted. This requires either advance knowledge of the input waveform before acquisition begins or the ability to adjust the acquisition parameters in response to data acquired. For example, if a periodic waveform is being acquired, the user may set the acquisition parameters to initial values, acquire data, adjust the acquisition parameters, to acquire data, etc., until the user is satisfied that the acquisition parameters are optimal for the waveform being acquired. This manual process may be slow, inaccurate and difficult to perform properly.
Other prior instruments include autosetting features wherein a microprocessor within the oscilloscope analyzes data acquired and adjusts its acquisition parameters accordingly. However, prior oscilloscopes which automatically adjust their acquisition parameters generally are not able to adjust them rapidly enough that data may be acquired both accurately and without significant delay. Accordingly, the need exists for an data acquisition system which quickly and accurately adjusts its acquisition parameters.